Process for the simultaneous stretch texturing of filament yarn

ABSTRACT

A process for the production of a textured endless yarn by the simultaneous false twisting and stretch texturing of an unstretched or incompletely stretched yarn of a high molecular weight, fibre-forming linear polymer, using at least two heating zones separated from each other in space between the delivery cylinder and the draw-off roller, in which process the yarn is delivered from the delivery cylinder to a first heating zone, heated in this heating zone without substantial mechanical stress at a low yarn tension to a yarn temperature above the glass temperature and thereafter, at a higher yarn tension built up between the first and second heating zone or in the first heating zone, it is stretched and simultaneously friction false-twisted and heat fixed between the delivery cylinder and the draw-off roller at a yarn temperature of below 160*C.

United States Patent Bach et al. Oct. 7, 1975 [5 PROCESS FOR THE SIMULTANEOUS 3,462,938 8/1969 Mehta 57/157 TS STRETCH TEXTURING OF FILAMENT 3,650,103 3/1972 Farrar....,..... 57/34 HS YARN 3,651,633 3/1972 Steinmilller 57/157 TS X 3,685,276 8/1972 Scherzberg i i 57/157 TS [75] Inventors: Hans Bach, Dormagen; Udo Hansel, 3,724,191 4/1973 Hooper et al.. 57/157 TS X Nieyenheim; Karl-August Hahnth, 3,796,036 3/1974 Parker 57/157 TS Dormagen; Hans-Dieter Jurischka, Dormagen; Rudolf J iirgen Klee,

Dormagen, all of Germany Bayer Aktiengesellschaft, Leverkusen-Bayerwerk, Germany Filed: Dec. 5, 1973 Appl. No.: 421,984

Assignee:

Foreign Application Priority Data Dec. 5, 1972 Germany 2259434 References Cited UNITED STATES PATENTS 9/1961 Evans 57/157 TS X 9/1966 Fitton et al.. 12/1966 Scragg 57/34 HS Primary Examiner-Donald E. Watkins Attorney, Agent, or Firm-Plumley & Tyner [57] ABSTRACT A process for the production of a textured endless yarn by the simultaneous false twisting and stretch texturing of an unstretched or incompletely stretched yarn of a high molecular weight, fibre-forming linear polymer, using at least two heating zones separated from each other in space between the delivery cylinder and the draw-off roller, in which process the yarn is delivered from the delivery cylinder to a first heating zone, heated in this heating zone without substantial mechanical stress at a low yarn tension to a yarn temperature above the glass temperature and thereafter, at a higher yarn tension built up between the first and second heating zone or in the first heating zone, it is stretched and simultaneously friction false-twisted and heat fixed between the delivery cylinder and the draw-off roller at a yarn temperature of below 160C.

6 Claims, 5 Drawing Figures US. Patent Oct. 7,1975 Sheet 2 of2 3,910,027

FIGS

PROCESS FOR THE SIMULTANEOUS STRETCH TEXTURING OF FILAMENT YARN This invention relates to a process for the production of a textured filament yarn by simultaneous false twisting and stretching an unstretched or incompletely stretched thread of a high molecular weight, linear, fibre-forming polymer, in particular a polyester, in which the amorphous threads are first heated to temperatures above the glass temperature without substantial mechanical stress before the usual twist fixing is carried out.

Smooth stretching of polyester threads between a heated roller and a stretching roller is already known. The thread is looped several times round the heated roller which heats the thread to a temperature above the glass temperature. Behind the heated roller is usually a stretching pin to fix the stretching point and another contact heating element for fixing. The stretched yarn is then textured on special texturing machines.

Consecutive stretching and texturing machines are also known, in which the yarn is first stretched between two rollers in the usual manner and then textured in a separate zone between a stretching roller and another roller with a twisting device and a twist fixing device between them.

Another process is characterised in that an unstretched polyester filament yarn is first stretched in a ratio of between 1 1.20 and l 3.80 in a heating zone between the delivery rollers at temperatures of 90 to 170C and then cooled and then restretched and, at the same time, fixed in a second heating zone at temperatures of 160 to 230C so that the total stretching ratio is in the range of 1 :2.5 to 1 4.5.

So-called simultaneous stretch texturing has also been described, in which the yarn is simultaneously stretched, false-twisted and textured between the delivery roller and draw-off roller. This method gives rise to difficulties in spreading the yarn and moreover, in order to prevent breakage of the filament, especially at high thread velocities at which the thread is subjected to severe tension from the twisting device, it is necessary either to use short heating elements, which are a constant source of irregularities in the textured yarn due to the excessively high temperature differences between the heating element and the thread, or to reduce the stretching ratio substantially which reduces the elasticity and the crimp stability.

In German Offenlegungschrift No 2,157,663 it has been proposed to use preheating elements immediately in front of the main heating elements used for twisting and fixing; these have been proposed especially for the purpose of the simultaneous stretch texturing for polyester threads. With this method, however, it is impossible to stretch the filaments fully without breaking them. In the method described in the above mentioned German Offenlegungschrift, i.e., that of stretching to a ratio of between 1.5 and 55m a first heating zone, filament breakage occurs at a stretching ratio of about 1 3. Because of the insufficiently complete stretching of ,the filament, it is necessary to use untreated filaments with a titre in order to obtain the same titre after spinning, and this entails increased spinning costs. Moreover, the elasticity and crimp stability properties are still not optimal. It must also be taken into account that, at the texturing speeds employed in the present invention of 200 to 600 metres per minute and when employing the method of friction false twisting which is necessary in this case, the process described above leads to such a high proportion of filament breakages even at stretching ratios below 1 3 that it can no longer be employed under these conditions. It is an object of this invention to reduce or substantially to obviate the disadvantages of the methods described above.

It has now been found that the simultaneous stretch texturing of fibre-forming polymers in particular polyesters, can be carried out to the same degree of stretching on long heating elements used for fixing without entailing the risk of breakage of the filaments provided that the amorphous or incompletely stretched threads are heated to a temperature above the glass tempera ture and are not subjected to any substantial mechanical stress below the glass temperature.

This invention therefore relates to a process for the production of a textured filament yarn by the simultaneous false twisting and stretch texturing of unstretched or incompletely stretched threads of high molecular weight, fibre-forming, linear polymers, in particular polyesters, using at least two heating zones separated from each other in space between delivery cylinder and draw-off roller, in which process the threads are delivered from the delivery cylinder to a first heating zone at a texturing velocity of 200 to 600 metres per minute, are heated in this heating zone to a temperature between T glass temperature and T 50C while substantially free from mechanical stress and at thread tensions of less than 0.05 p/dtex, and then, while under tensions of 0.1 to 0.5 p/dtex which are built up between the first and second heating zone or already in the first heating zone, they are stretched in the ratio of between 1 1.5 and l 4.5 and simultaneously subjected to friction false-twisting and heat fixing at thread temperatures above 160C between the delivery cylinder and the draw-off roller.

With the process according to the invention, even virtually completely unorientated material from the spinning spool which has been spun e.g. at 900 to 1 metres per minute can be stretch textured at high thread velocities of more than 100 metres per minute with practically no breakage of the filaments without any need to emply lower stretching ratios than in a conventional smooth stretching process or to use short heating elements for twist fixing, with the disadvantages which this entails of giving rise to high temperature differences and hence the risk of irregularities in the texture. The tensile strength and crimp stability of the textured yarn can thereby be substantially increased of the expense of spinning filaments to a finer titre can be avoided.

FIG. 1 represents the process in its most generalised form.

The unstretched or incompletely stretched yarn from spool 1 is delivered to a first heating zone 5 by way of a deflecting roller 2, yarn brakes 3 and delivery cylinders 4. In heating zone 5, the yarn is heated to a temperature between T glass temperature and T 50C without any substantial mechanical stress and at yarn tensions of less than 0.05 p/dtex. This can be achieved by using, as the first heating zone, either a heated roller 12 (see FIG. 2) or a contact heating element 13 (see FIG. 3) or a hot pin 14 (see FIG. 4). In this case, it is important that the yarn should be passed over a stretch ing pin 15 (see FIGS. 2, 3 and 4) between the first and second heating zone. The friction between the yarn and the stretching pin keeps the yarn tension in the first heating zone sufficiently low to ensure that the yarn will be heated up in this first zone without substantial mechanical stress. The stretching pin may be arranged anywhere between the heating zones 5 and 6 which are separated from each other by a distance of 0.2 to l m. The position of the pin is determined, among other things, by the titre of the ,yam. After passing over the stretching pin, the yarn has a tension of 0.1 to 0.5 p/dtex, preferably 0.3 to 0.4 p/dtex.

In another embodiment of the invention, no stretching pin is used. According to the invention, the yarn is in this case passed over a hot pin 14 (FIG. 5) with a looping angle of at least 270, preferably at least 720 before it enters the heating and fixing zone 6. By looping the yarn over the hot pin with a looping angle of at least 270, it becomes heated to a temperature above or equal to its glass temperature substantially without any mechanical stress and at tension of less than 0.05 p/dtex. At the same time, the increasing friction due to the multiple looping of the yarn round the hot pin builds up the yarn tension so that the yarn leaves the hot pin at the desired tension of 0.1 to 0.5 p/dtex, preferably 0.3 to 0.4 p/dtex before entering the second heating zone. In both the embodiments described above, i.e. both when using the hot pin alone (FIG. 5) and when an unheated stretching pin following a first heating zone, the second heating zone 6 serves as heating and fixing zone in which the false twist 8 is fixed. To ensure that this twist will be sufficiently firmly fixed, the heating and fixing zone is followed by a sufficiently long cooling zone 7 in which the yarn is cooled to a temperature close to the glass temperature before entering the twisting zone. In the case of coarser yarn, cooling in this zone is preferably positive (e.g. by means of conduction cooling devices). After passing over the false twisting device, the yarn is looped several times round a roller 9, if necessary to receive a thermal after-treatment after passing through -an additional heating zone (conduction heating or convection heating), and from there it reaches a dressing apparatus 10. The yarn is then wound on a winding device 11.

The total stretch measured between the delivery cylinder 4 and the draw-off roller 9 is between 1 1.5 and l: 4.5. The process according to the invention is suitable for the texturing of fibre-forming polyamides and polyesters.

The polyester filaments used are produced from high molecular weight linear polyester, in particular by the melt spinning process. Products of terephthalic acid and ethylene glycol or cyclohexane-1,4-dimethanol or mixtures of ethylene glycol and cyclohexanel ,4- dimethanol are particularly suitable.

From among the various synthetic thermoplastic filaments, those of polyamides (polycaprolactam and polyhexamethylene adipamide) are also particularly suitable for the process.

The following Examples are to further illustrate the invention without limiting it.

EXAMPLE 1 A polyester yarn with a titre before treatment of 290 dtex and composed of 17 individual filaments was conveyed to the delivery cylinder 4 over a deflecting device 2 and yarn brake 3 and then looped practically tension-free with a looping angle of 360C over a hot pin 14 with a diameter of 70 mm which is heated to l 15C (see FIGS. 1 and 4). The yarn was then passed over a stretching pin 15 and stretched in the ratio of l 3.76 between the delivery cylinder 4 and roller 9, the stretching pin serving to fix the stretching point. The twist was then produced by means of an internal friction false-twist 8 the surface velocity of which was 3- times the texturing velocity of the yarn, which was 400 metres per minute. The twist yarn bundle was then fixed on a conduction heating element 6 which was at a temperature of 200C. The yarn which had now been textured was then set by partly returning it over the heating and fixing element (contact length 18 cm). A rinsing oil was then applied and the yarn is wound. The final titre was 78 f 17 dtex.

The yarn had a crimp 1) of 26 percent and a crimp stability KB of 62 percent. The tensile strength was 38 Rkm and the elongation 25 percent. The irreversible shrinkage was less than 3 percent. According to DIN 0053840 draft 1970; KB crimp stability at 1 p/dtex permanent load EXAMPLE 2 A polyester yarn with a teatment of 320 dtex and composed of 26 individual filaments was simultaneously stretched and textured as in example I but stretching was to a ratio of l 4.11. The temperature of the hot pin 14 was 125C and the looping angle was 720. The conduction heating element 6 was adjusted to a temperature of 220 and the draw-off rate to 600 metres per minute. The speed of rotation of the twist 8 was 20,000 revs per min. During the heating-up period within the set process, the yarn was adjusted to a relaxation of 8 percent. The final titre was 78 f 26 dtex.

EK" 28 -KB 55 Tensile strength 40 Rkm Elongation 22 Shrinkage 1.2

EXAMPLE 3 A heated roller 12 was fitted in this case instead of the hot" pin (see FIG. 2).

A polyester thread with a titre before treatment of 650 dtex and composed of 34 individual filaments was simultaneously stretched and textured as in examples 1 and 2.

The temperature of the heated roller 12 was adjusted to C and the yarn was looped round seven times. A stretching pin 15 round which the yarn was looped once was arranged at a distance of 2 cm. The stretching ratio was 1 3.76.

The conduction heating element 6 had a length of l m and was contacted twice by the thread by reversal of direction; its temperature was 220C. The draw-off rate was 300 metres per minute. The twister 8 rotated at 14,000 revs per min. The thermal after-treatment was carried out in a second convection heating device 1.5 m in length at a temperature of C. Relaxation of the textured yarn was adjusted to 12 percent. The cooling zone 7 was 60 cm in length and comprised a conduction cooling element with a surface temperature of 30C. The final titre was 167 f 34 dtex EK 26 percent, KB l p/dtex 65 percent, Tensile strength 37,0 Rkm, Elongation 27 Shrinkage l We claim:

1. Process for the production of a textured endless yarn by the simultaneous false twisting and stretch texturing of unstretched or not completely stretched yarn of high molecular weight, fibre-forming linear polymers, in particular polyesters, using at least two heating zones separated from each other in space between the delivery cylinder and the draw-off roller, in which process the yarn is delivered from the delivery cylinder to a first heating zone at texturing velocities of 200 to 600 metres per minute, is heated in this heating zone without substantial mechanical stress at yarn tensions of less than 0.05 p/dtex to a yarn temperature between T glass temperature and T 50C, and thereafter, at yarn tensions of 0.1 to 0.5 p/dtex, which build up between the first and second heating zone, it is stretched in the ratio of between 1 1.5 and l 4.5 and simultaneously friction false twisted and heat fixed between the delivery cylinder and drawoff roller at yarn temperatures of below 160C.

2. Process according to claim 1, wherein the yarn tension of 0.1 to 0.5 p/dtex which build up between the first and second heating zone are built up on a stretching pin.

3. Process according to claim 1, wherein the yarn tension of 0.1 to 0.5 p/dtex which builds up between the first and second heating zone are built up on a stretching pin.

-4. Process according to claim 3, wherein the first heating zone comprises a material selected from the group consisting of a hot pin, a heatable roller and a conduction heating element.

5. Process according to claim 1, wherein the yarn tension of 0.1 to 0.5 p/dtex is built up on a hot pin heated to temperatures above 270C which constitutes the first heating zone and around which the yarn is looped.

6. Process according to claim 1, wherein the yarn tensions which build up between the first and second heating zone are 0.3 to 0.4 p,/dtex. =l 

1. Process for the production of a textured endless yarn by the simultaneous false twisting and stretch texturing of unstretched or not completely stretched yarn of high molecular weight, fibreforming linear polymers, in particular polyesters, using at least two heating zones separated from each other in space between the delivery cylinder and the draw-off roller, in which process the yarn is delivered from the delivery cylinder to a first heating zone at texturing velocities of 200 to 600 metres per minute, is heated in this heating zone without substantial mechanical stress at yarn tensions of less than 0.05 p/dtex to a yarn temperature between T glass temperature and T + 50*C, and thereafter, at yarn tensions of 0.1 to 0.5 p/dtex, which build up between the first and second heating zone, it is stretched in the ratio of between 1 : 1.5 and 1 : 4.5 and simultaneously friction false twisted and heat fixed between the delivery cylinder and draw-off roller at yarn temperatures of below 160*C.
 2. Process according to claim 1, wherein the yarn tension of 0.1 to 0.5 p/dtex which build up between the first and second heating zone are built up on a stretching pin.
 3. Process according to claim 1, wherein the yarn tension of 0.1 to 0.5 p/dtex which builds up between the first and second heating zone are built up on a stretching pin.
 4. Process according to claim 3, wherein the first heating zone comprises a material selected from the group consisting of a hot pin, a heatable roller and a conduction heating element.
 5. Process according to claim 1, wherein the yarn tension of 0.1 to 0.5 p/dtex is built up on a hot pin heated to temperatures above 270*C which constitutes the first heating zone and around which the yarn is looped.
 6. Process according to claim 1, wherein the yarn tensions which build up between the first and second heating zone are 0.3 to 0.4 p/dtex. 